Metalloporphyrinic frameworks have been studied in many fields. However, their electrochemical properties were seldom reported. This work reports the synthesis and the electrochemical application of a new bimetallic metalloporphyrinic framework, [Cu2-Co[5,10,15,20-(4-carboxyphenyl)porphyrin](H2O)2]·0.5DMF·5H2O (Cu-CoTCPP) in which [5,10,15,20-(4-carboxyphenyl)porphyrin]Co(II) (CoTCPP) struts are bound by Cu(II)–carboxylate clusters (Cu2(COO)4). Cu-CoTCPP was synthesized by the solvothermal method and characterized by various techniques, including XRD, IR, UV-vis, elemental analysis, TG, and TEM. Cu-CoTCPP showed novel bifunctional electrocatalytic ability toward the reduction/oxidation of H2O2 and the oxidation of NaNO2, which might be due to Cu and Co central ions, respectively. With the assistance of multi-walled carbon nanotubes (MWCNTs), Cu-CoTCPP showed further improved sensing performance toward H2O2. The linear detection ranges of the Cu-CoTCPP/MWCNTs/GCE for H2O2 and NaNO2 are 5.0 × 10−7 to 1.8 × 10−4 M and 2.5 × 10−6 to 1.1 × 10−3 M, respectively, with the detection limits of 2.4 × 10−7 M and 1.7 × 10−7 M, and the sensitivity of 168 and 439 mA mol−1 L cm−2. The bifunctional electrocatalytic ability and the excellent performance imply that the metalloporphyrinic frameworks are promising candidates for fabricating electrochemical sensors.

•Thermal decomposition of coordination polymer (CP) without morphology destroying.•Preparation of porous Mn2O3 nanorods via decomposition of CP.•Mn2O3-Au nanocomposite.•Good performance in hydrazine electrochemical sensing.Porous Mn2O3 nanorods were prepared via the decomposition of a coordination polymer precursor, as evidenced by XRD and TEM results. Electrochemistry results showed obvious electrocatalytic activity of Mn2O3 nanorods toward the oxidation of hydrazine. When Au nanoparticles were loaded onto Mn2O3 nanorods, the performance in hydrazine determination was improved obviously. The sensitivity of 500 mA mol-1 L cm−2 was obtained in linear range of 2×10−6−1.3×10−3 mol L−1, and the detection limit was 1.1×10−6 mol L−1.

•A new metal–biomolecule coordination polymer in the shape of nanorods.•Novel bidirectional electrocatalytic ability toward the reduction/oxidation of H2O2.•Perfect electrochemical sensing performance with the assistance of CNTs.Metal organic coordination polymers (CPs), as most attractive multifunctional materials, have been studied extensively in many fields. However, metal–biomolecule CPs and CPs' electrochemical properties and applications were studied much less. We focus on this topic aiming at electrochemical biosensors with excellent performance and high biocompatibility. A new nanoscaled metal–biomolecule CP, Mn–tyr, containing manganese and tyrosine, was synthesized hydrothermally and characterized by various techniques, including XRD, TEM, EDS, EDX mapping, elemental analysis, XPS, and IR. Electrode modified with Mn–tyr showed novel bidirectional electrocatalytic ability toward both reduction and oxidation of H2O2, which might be due to Mn. With the assistance of CNTs, the sensing performance of Mn–tyr/CNTs/GCE was improved to a much higher level, with high sensitivity of 543 mA mol−1 L cm−2 in linear range of 1.00×10−6–1.02×10−4 mol L−1, and detection limit of 3.8×10−7 mol L−1. Mn–tyr/CNTs/GCE also showed fast response, high selectivity, high steadiness and reproducibility. The excellent performance implies that the metal–biomolecule CPs are promising candidates for using in enzyme-free electrochemical biosensing.

•Synthesis of nanoscale coordination polymers (NCPs) via a sonochemical method.•Using NCPs as a new class of materials for electrochemical biosensing.•Great performance as enzyme-free H2O2 sensors.•Indicating that nanocrystallization of the CPs improved the sensing performance.Coordination polymers attract increasing attention as unique multifunctional hybrid materials. However, researches of CPs as electrochemical biosensors are rare. In this work, we developed a surfactant-assisted sonochemical method to synthesize nanoscale coordination polymers ([Cu(tyr)2]n and [Cu(asp)]n, nanorods with width of 100–200 nm), based on which enzyme-free electrochemical biosensors for H2O2 were prepared. Their sensing performance was improved by nanocrystallization, giving detection limits of 1.0×10−5 and 2.0×10−6 mol dm−3, linear ranges of 4.0×10−5–6.3×10−3 and 3.4×10−5–6.8×10−4 mol dm−3, and sensitivity of 70 and 110 mA mol−1 dm3 cm−2, respectively.

The burgeoning demand for clean and energy-efficient fuel cell system requires electrocatalysts to deliver greater activity and selectivity. Bimetallic catalysts have proven superior to single metal catalysts in this respect. This work reports the preparation, characterization, and electrocatalytic characteristics of a new bimetallic nanocatalyst. The catalyst, Pt–Au–graphene, was synthesized by electrodeposition of Pt–Au nanostructures on the surface of graphene sheets, and characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), and voltammetry. The morphology and composition of the nanocatalyst can be easily controlled by adjusting the molar ratio between Pt and Au precursors. The electrocatalytic characteristics of the nanocatalysts for the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) were systematically investigated by cyclic voltammetry. The Pt–Au–graphene catalysts exhibits higher catalytic activity than Au–graphene and Pt–graphene catalysts for both the ORR and the MOR, and the highest activity is obtained at a Pt/Au molar ratio of 2:1. Moreover, graphene can significantly enhance the long-term stability of the nanocatalyst toward the MOR by effectively removing the accumulated carbonaceous species formed in the oxidation of methanol from the surface of the catalyst. Therefore, this work has demonstrated that a higher performance of ORR and the MOR could be realized at the Pt–Au–graphene electrocatalyst while Pt utilization also could be greatly diminished. This method may open a general approach for the morphology-controlled synthesis of bimetallic Pt–M nanocatalysts, which can be expected to have promising applications in fuel cells.

Amorphous β-Bi2O3 nanoparticles were synthesized directly via a liquid phase microwave reaction, and changed gradually into well crystallized sheet-like nanoparticles of β-Bi2O3 or α-Bi2O3 during the following calcining at lower (300 °C) or higher (350 °C) temperature. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and diffuse reflectance spectroscopy (DRS) were used to characterize the samples. The photocatalytic activity of the samples under simulated sunlight was also investigated by taking the degradation of rhodamine B (RB) as model reaction. β-Bi2O3 showed lower band gap energy and high absorbance in wider visible light region than α-Bi2O3 did, resulting in its higher photocatalytic activity. It was also found that higher crystallinity can improve the activity.

Metalloporphyrinic frameworks have been studied in many fields. However, their electrochemical properties were seldom reported. This work reports the synthesis and the electrochemical application of a new bimetallic metalloporphyrinic framework, [Cu2-Co[5,10,15,20-(4-carboxyphenyl)porphyrin](H2O)2]·0.5DMF·5H2O (Cu-CoTCPP) in which [5,10,15,20-(4-carboxyphenyl)porphyrin]Co(II) (CoTCPP) struts are bound by Cu(II)–carboxylate clusters (Cu2(COO)4). Cu-CoTCPP was synthesized by the solvothermal method and characterized by various techniques, including XRD, IR, UV-vis, elemental analysis, TG, and TEM. Cu-CoTCPP showed novel bifunctional electrocatalytic ability toward the reduction/oxidation of H2O2 and the oxidation of NaNO2, which might be due to Cu and Co central ions, respectively. With the assistance of multi-walled carbon nanotubes (MWCNTs), Cu-CoTCPP showed further improved sensing performance toward H2O2. The linear detection ranges of the Cu-CoTCPP/MWCNTs/GCE for H2O2 and NaNO2 are 5.0 × 10−7 to 1.8 × 10−4 M and 2.5 × 10−6 to 1.1 × 10−3 M, respectively, with the detection limits of 2.4 × 10−7 M and 1.7 × 10−7 M, and the sensitivity of 168 and 439 mA mol−1 L cm−2. The bifunctional electrocatalytic ability and the excellent performance imply that the metalloporphyrinic frameworks are promising candidates for fabricating electrochemical sensors.

The burgeoning demand for clean and energy-efficient fuel cell system requires electrocatalysts to deliver greater activity and selectivity. Bimetallic catalysts have proven superior to single metal catalysts in this respect. This work reports the preparation, characterization, and electrocatalytic characteristics of a new bimetallic nanocatalyst. The catalyst, Pt–Au–graphene, was synthesized by electrodeposition of Pt–Au nanostructures on the surface of graphene sheets, and characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray powder diffraction (XRD), and voltammetry. The morphology and composition of the nanocatalyst can be easily controlled by adjusting the molar ratio between Pt and Au precursors. The electrocatalytic characteristics of the nanocatalysts for the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) were systematically investigated by cyclic voltammetry. The Pt–Au–graphene catalysts exhibits higher catalytic activity than Au–graphene and Pt–graphene catalysts for both the ORR and the MOR, and the highest activity is obtained at a Pt/Au molar ratio of 2:1. Moreover, graphene can significantly enhance the long-term stability of the nanocatalyst toward the MOR by effectively removing the accumulated carbonaceous species formed in the oxidation of methanol from the surface of the catalyst. Therefore, this work has demonstrated that a higher performance of ORR and the MOR could be realized at the Pt–Au–graphene electrocatalyst while Pt utilization also could be greatly diminished. This method may open a general approach for the morphology-controlled synthesis of bimetallic Pt–M nanocatalysts, which can be expected to have promising applications in fuel cells.